I've never been in a situation like that, but if I were to speculate, I'd say tell the truth. You can always include a detailed explanation with the form (i.e. that it was a misdemeanor, how long ago it happened, how old you were at the time, etc.).
I guess no one in this forum will be able to give you a definite answer to your question unless they've been in your particular situation. If still in doubt - seek professional advice.
Good luck!